Image forming apparatus for preventing abnormally discharged image

Patent metadata

Field	Value
Publication number	US-9798266-B2
Application number	US-201615221923-A
Country	US
Kind code	B2
Filing date	Jul 28, 2016
Priority date	Jul 31, 2015
Publication date	Oct 24, 2017
Grant date	Oct 24, 2017

Abstract

An image forming apparatus includes: a first exposing unit exposing a surface of a charged photosensitive member to form a latent image; a second exposing unit exposing the surface of the photosensitive member after the surface of the photosensitive member passes a transfer position at which a toner image obtained by causing toner to adhere to the latent image is transferred to a transferred body and before the surface of the photosensitive member reaches a charging position; and a control unit varying a length of a period from a timing at which a portion of the photosensitive member exposed by the second exposing unit is initially charged by the charging member to a timing at which the first exposing unit starts formation of the latent image when performing image formation based on a print signal, based on information related to a photosensitive layer thickness of the photosensitive member.

First claim

What is claimed is:

1. An image forming apparatus performing image formation on recording material based on a print signal, the image forming apparatus comprising:
a photosensitive member;
a charging member which charges the photosensitive member at a charging position;
a first exposing unit which exposes a surface of the charged photosensitive member to form a latent image;
a second exposing unit which exposes the surface of the photosensitive member after the surface of the photosensitive member passes a transfer position at which a toner image obtained by causing toner to adhere to the latent image is transferred to a transferred body and before the surface of the photosensitive member reaches the charging position; and
a control unit which controls a period from a timing at which a portion of the photosensitive member exposed by the second exposing unit is initially charged by the charging member to a timing at which the first exposing unit starts formation of the latent image when performing image formation based on the print signal,
wherein the control unit varies a length of the period based on information related to a thickness of a photosensitive layer of the photosensitive member.

2. The image forming apparatus according to claim 1 , wherein the control unit performs control so that the smaller the thickness of the photosensitive layer of the photosensitive member, the shorter the period.

3. The image forming apparatus according to claim 1 , wherein the information related to the thickness of the photosensitive layer of the photosensitive member is information acquired based on any information related to the number of sheets of recording material on which image formation has been performed, the number of rotations of the photosensitive member as a rotating body, the number of sheets of recording material having passed through the image forming apparatus, and a time during which the photosensitive member is charged by the charging member.

4. The image forming apparatus according to claim 1 , wherein the control unit further controls a length of the period based on information related to a charging capability of the charging member.

5. The image forming apparatus according to claim 4 , wherein the charging member comes into contact with the photosensitive member at the charging position, and information related to the charging capability is acquired based on at least any of a resistance value of the charging member, a time during which voltage is applied to the charging member, and an integrated value of a current flowing through the charging member.

6. The image forming apparatus according to claim 1 , wherein the control unit controls the period so that the first exposing unit performs exposure to form the latent image on a region of the surface of the photosensitive member on a further upstream side in a movement direction of the surface of the photosensitive member than a region of the surface of the photosensitive member charged by the charging member in a state where a charging current equal to or larger than a desired value flows through the charging member.

7. The image forming apparatus according to claim 1 , wherein when the image formation is performed based on the print signal, a timing at which the charging member starts charging the photosensitive member arrives earlier than a timing at which the second exposing unit starts exposure.

8. The image forming apparatus according to claim 1 , wherein the charging member comes into contact with the photosensitive member at the charging position, and when the charging member charges the photosensitive member, only DC voltage is applied to the charging member.

9. The image forming apparatus according to claim 1 , wherein the transferred body is either recording material or an intermediate transfer member to which a toner image is transferred from the photosensitive member and which transfers the transferred toner image to recording material.

10. An image forming apparatus performing image formation on recording material based on a print signal, the image forming apparatus comprising:
a photosensitive member;
a charging member which charges the photosensitive member at a charging position;
a first exposing unit which exposes a surface of the charged photosensitive member to form a latent image;
a second exposing unit which exposes the surface of the photosensitive member after the surface of the photosensitive member passes a transfer position at which a toner image obtained by causing toner to adhere to the latent image is transferred to a transferred body and before the surface of the photosensitive member reaches the charging position; and
a control unit which controls a period from a timing at which a portion of the photosensitive member exposed by the second exposing unit is initially charged by the charging member to a timing at which the first exposing unit starts formation of the latent image when performing image formation based on the print signal,
wherein the control unit varies a length of the period based on environmental information.

11. The image forming apparatus according to claim 10 , wherein the control unit performs control based on an absolute moisture content.

12. The image forming apparatus according to claim 10 , further comprising a temperature and humidity sensor, wherein the environmental information is information acquired based on temperature and humidity detected by the temperature and humidity sensor.

13. The image forming apparatus according to claim 10 , wherein the control unit further controls a length of the period based on information related to a charging capability of the charging member.

14. The image forming apparatus according to claim 13 , wherein the charging member comes into contact with the photosensitive member at the charging position, and information related to the charging capability is acquired based on at least any of a resistance value of the charging member, a time during which voltage is applied to the charging member, and an integrated value of a current flowing through the charging member.

15. The image forming apparatus according to claim 10 , wherein the control unit controls the period so that the first exposing unit performs exposure to form the latent image on a region of the surface of the photosensitive member on a further upstream side in a movement direction of the surface of the photosensitive member than a region of the surface of the photosensitive member charged by the charging member in a state where a charging current equal to or larger than a desired value flows through the charging member.

16. The image forming apparatus according to claim 10 , wherein when the image formation is performed based on the print signal, a timing at which the charging member starts charging the photosensitive member arrives earlier than a timing at which the second exposing unit starts exposure.

17. The image forming apparatus according to claim 10 , wherein the charging member comes into contact with the photosensitive member at the charging position, and when the charging member charges the photosensitive member, only DC voltage is applied to the charging member.

18. The image forming apparatus according to claim 10 , wherein the transferred body is either recording material or an intermediate transfer member to which a toner image is transferred from the photosensitive member and which transfers the transferred toner image to recording material.

19. An image forming apparatus performing image formation on recording material

Assignees

• Canon Kk

Inventors

• Agata Shinichi
• Ikada Kosuke

Classifications

• G03G15/5033

  by measuring the photoconductor characteristics, e.g. temperature, or the characteristics of an image on the photoconductor · CPC title

• G03G15/0266 Primary

  Arrangements for controlling the amount of charge · CPC title

• G03G21/08

  using optical radiation · CPC title

• G03G15/553

  Monitoring or warning means for exhaustion or lifetime end of consumables, e.g. indication of insufficient copy sheet quantity for a job · CPC title